


4 Times Sherlock Kissed John For Science

by ckerased



Category: Sherlock (TV)
Genre: First Kiss, Fluff, Kissing, M/M, Science Experiments
Language: English
Status: Completed
Published: 2012-01-27
Updated: 2012-01-27
Packaged: 2017-10-30 05:06:30
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 5
Words: 6,970
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/328071
Author URL: https://archiveofourown.org/users/ckerased/pseuds/ckerased
Summary: <blockquote class="userstuff">
              <p>After Sherlock reads an article on the benefits of kissing, he convinces John to take place in a few snogging sessions. . . for science! Lots of medical lingo. There are five parts in all.</p>
            </blockquote>





	1. A Study in Blood Pressure

**Author's Note:**

> Disclaimer: I do not own Sherlock Holmes, John Watson or 221B Baker Street. Not in the slightest.
> 
> Warnings: None, thus far.
> 
> Word Count (this part): 1,237
> 
> A/N: Any medical terms you do not understand should be at the very bottom of the fic, just to help for clarification.

"John, could I ask a favor of you?" Sherlock asked, never taking his eyes off the screen of his laptop.

John glanced up from the newspaper he was reading to look at Sherlock, quirking an eyebrow in interest.

"What could I  _possibly_  do as a favor to you, Sherlock?" John asked.

Sherlock looked up from his laptop then, studying John's facial expression to determine whether he was genuinely considering assisting him. After a short moment of examination, Sherlock decided his flatmate was interested enough and let out a long, drawn-out breath.

"To start, I need you to listen through my  _entire_  explanation without interrupting me. Can you do that?"

John nodded silently.

"Good," Sherlock responded.

He cleared his throat, closed his laptop and set it aside before continuing.

"Let me give you some background information before I begin." Sherlock cleared his throat once more. "I recently stumbled across an article that listed some benefits of kissing to a person's health. The first one I read mentioned that blood pressure increases while kissing, but an article about the same matter said that a person's blood pressure  _decreases_. These conflicting 'results' on the same experiment debunks one of the articles' credentials, and I must find out which one is correct. Do you understand?"

John, who had dropped his newspaper at the word "kissing," was sitting with his mouth slacked in shock.

"I, uh. . . Wha- . . ." John attempted to stutter out a response. "I mean . . . erm, I  _understand_ , but what. . . What do you need me for, exactly?" He cleared his throat awkwardly.

Sherlock attempted to contain a smirk at John's reaction.

"I need to find out which one is correct, obviously. That is where you come in."

John was shaking his head, trying to stop himself from interrupting while also attempting to keep himself seated instead of dashing out of the flat.

"You could use anybody!"

"That is incorrect. The experiment has to be done on someone who is healthy and not at risk, based on family genetics, of having high or low blood pressure. I checked your family's medical history all the way back to your great-grandfather, Eugene. Not a single person on your family tree has had hyper or hypotension, making you the perfect test subject."

John refused to respond for a moment, silently cursing every individual who owed Sherlock a favor. Had they not owed him favors, Sherlock never would have found out that his family had an immaculate medical history: no heart attacks, no strokes, no hypertension, no genetic disorders. . . Nothing. His sister's alcoholism was the closest thing to a mental disorder in his entire family.

John knew there was no way to get out of this, now. When Sherlock was adamant about something, there was no dissuading him.

"Fine," John finally responded, disdain evident in his voice, "I'll do it."

Sherlock jumped up from his chair and ran into the kitchen. John heard some test-tubes clanking together, a glass something shatter and a worrisome-sounding thud within the first few seconds. He was too annoyed to care, though. The doctor dropped his face into his hands, trying to will away this entire situation.

After a few more minutes of listening to Sherlock toss things about, John heard hurried footsteps coming from the kitchen directly toward him. He lifted his face from his hands and looked up to see his flatmate standing in front of him with a sphygmomanometer in his hands and a stethoscope around his neck.

"Roll up your sleeve, John," Sherlock demanded, bending down on one knee next to John's armchair. "I know you've done this on thousands of patients, so I shouldn't have to tell you to relax."

John rolled up his sleeve until the fabric was bunched up at his shoulder. Sherlock immediately started snaking the cuff up John's arm until it reached his bicep, where he tightened it until it was snug, and fastened the Velcro parts together to keep it in place.

Sherlock leaned back to his normal kneeling position, placed the eartips of the stethoscope into his ears and began squeezing the bulb to inflate the cuff. When it was just tight enough, Sherlock stopped inflating it and placed the bell of the stethoscope on the crook of John's elbow. He began decreasing the pressure of the cuff slowly, and carefully watched the monitor while listening for John's heartbeat to determine John's systolic and diastolic pressure.

John let out a slow breath as Sherlock completely deflated the cuff and removed it from his arm. Sherlock ran over to his laptop, opened it, and typed the result into a Word document that was completely dedicated to this experiment.

Shortly after, Sherlock set aside his laptop once more and made his way back over to John.

"Perfect blood pressure for your age. Congratulations. Now, are you ready for the independent variable?"

John sighed but nodded nonetheless.

"Stand up. We're going to move to the couch, since I'm assuming you probably don't want me sitting on your lap with your psychosomatic pain and all that."

The doctor stood up, walked stiffly over to the couch and sat down. Sherlock followed suit, sitting directly next to his flatmate with his body turned slightly toward him. John just stared directly in front of himself at nothing, avoiding eye contact with Sherlock.

"You need to relax," Sherlock said, dangerously close to John's ear. "My result will be off if you don't calm down. Just close your eyes and pretend I'm some woman you have taken back to your flat after a nice date."

John closed his eyes as he felt cold fingers turn his face gently to his right. He felt surprisingly soft lips graze his and shuddered.

' _I can't believe I'm letting him do this,_ ' John thought as he felt the lips touch his again, a bit harder this time.

Sherlock began legitimately kissing John, cupping his face with his right hand and applying a bit more pressure than he had on the first kiss.

John began returning the kiss after a few seconds of hesitation. He rotated his body slightly in order to make the connection a little less difficult and started trying to gain some control in the situation. If he was going to be an experiment, he may as well perform to his full potential, he figured. Plus, his flatmate's lips were incredibly soft, and he was also quite. . .  _skilled_  with his tongue.

After a few minutes (3 minutes and 27 seconds, to be exact), Sherlock ended the kiss. By the time John had fully opened his eyes, Sherlock was across the room, grabbing the blood pressure apparatus and stethoscope.

"Now, let's take a look at the result, shall we?" Sherlock asked as he made his way back over to the doctor.


	2. A Study in O2 Saturation

**Notes for the Chapter:**

> Disclaimer: I do not own Sherlock Holmes, John Watson or 221B Baker Street. Not in the slightest.
> 
> Word Count (this part): 1,199

It was another normal day at 221B Baker Street; eyeballs in the microwave, other body parts in the fridge, test-tubes strewn about the kitchen table, newspaper clippings littering the walls. . .  _Normal_ for flat 221B.

What was  _not_  normal, however, was the fact that Sherlock was - once again – attempting to persuade John to take place in an experiment that involved kissing.

"You have done it once already!" Sherlock exclaimed irritably. "What makes a second time so different?"

John sighed in frustration, running his fingers through his short-cropped hair as he paced back and forth in front of the window overlooking Baker Street.

"What is this little experiment for again?" John asked, a hint of annoyance evident in his tone.

Sherlock watched every movement John made as though it was of utmost importance.

"I need to test the effect a person's heart rate has on his O2 saturation when he is forced to breathe through his nose."

"And why can't I just take a jog around the block?"

Sherlock tried not to roll his eyes as he responded, "Please think before you ask such questions. I need you to breathe through your nose. When a person jogs, he breathes through his mouth in order to acquire the maximum amount of oxygen per breath. It's not that I don't trust that you could try to breathe through your nose; it's that it is not physically possible for your body to continue functioning properly if you do not intake enough oxygen to compensate for the large amount of oxygen you lose by using so many muscles simultaneously. Kissing, however, is considered a light exercise because it raises a person's heart-rate by less than 30 BPM, so it is no problem for a person to breathe primarily through his nose."

Sherlock let out a short huff before continuing, "Plus, I already have data on the changes in O2 saturation when a man does light exercise and breathes primarily through his mouth. I also have data on a man who went jogging to get his heart rate up even higher than what light exercise can provoke. The only O2 saturation statistic I am missing is the change that occurs when a person performs light exercise while breathing through his nose."

Sherlock continued to watch John pace back and forth.

John stopped pacing and turned to stare at Sherlock with a confused expression. He looked as though he may say something, but no words came out.

' _What's the big deal? You've done it once already, so why do you even care that he needs you to do it again?_ ' John thought to himself.

Another, more devious sounding version of his normal voice popped into his head saying, ' _Maybe it's because you liked it so much last time, and you're worried you might not be able to stop yourself if you kiss him again._ '

John shook his head violently, ' _NO. That's not my problem! I am a perfectly normal,_ heterosexual _doctor who does **not**  have feelings for my very much male _ _flatmate._ '

' _Prove it, then,_ ' was all the devious John-voice responded.

"Fine!" John accidentally thought aloud.

The detective quirked an eyebrow at John, the doctor's sudden outburst mixed with some troubling facial expressions he made leading Sherlock to believe that he had just observed a pretty bloody battle occur in John's mind.

"Are you alright?" Sherlock asked, tearing John out of his trance.

John jumped a bit, completely caught off guard by his flatmate's question. He turned to look at the detective and nodded slightly.

"Uhh. Yes." John cleared his throat. "Just, uh. . . Yes, I'm fine."

Sherlock gave the doctor a very skeptical look but shrugged it off.

"So, will you help me?" Sherlock asked.

John let out a slow, deliberate breath to calm himself. He was a little worried, because he was not sure if he was going to be able to to prove that little nagging voice wrong.

' _The best I can do is try, right? I'll do my own experiment while Sherlock does his. We both win_ ,' John thought.

Upon making his decision, John made his way over to the couch Sherlock was sitting on.

"I've done it once already. . . What will another time hurt?" John said. "Just get this over with, please."

Just as the doctor was sitting down, Sherlock was standing up. The detective strolled over to a decently large desktop monitor on a set of wheels and began to push it toward John. When Sherlock reached him, John noticed a sticker on the side that read, "Property of St. Bartholomews Hospital."

"Do I even want to know how you managed to get a pulse oximeter from Bart's?" John asked, truly worried about what the answer might be.

Sherlock simply grinned as he plugged the monitor into a power strip and attached a finger clip onto John's right index finger. He quickly typed John's initial O2 saturation (99%) into his laptop and sat down next to his flatmate.

"I would tell you, but you would get angry," Sherlock finally responded. "Anger would cause your heart rate to increase, which would in turn alter my results." The detective paused for a moment, "Now, we need to do this for at least five minutes. If you stop, we have to start over. Any questions?"

John shook his head.

"Good," Sherlock said before he captured John in a kiss that immediately dropped his O2 saturation to 96%.

**Notes for the Chapter:**

> O2 saturation - Measures the percentage of hemoglobin binding sites in the bloodstream occupied by oxygen. Essentially tells you how much oxygen is getting where it needs to be.
> 
> Oximeter – A device that monitors a person's O2 saturation through a clip that goes on his or her finger.
> 
> Next chapter: Sherlock takes John to the pool to study his lung capacity before and after kissing.


	3. A Study in Lung Capacity

**Notes for the Chapter:**

> Disclaimer: I do not own Sherlock Holmes, John Watson or 221B Baker Street. Not in the slightest.
> 
> Warnings: One f-bomb.
> 
> Word Count (this part): 2,544

It had been a few weeks since the last kissing experiment had taken place, and John was beginning to believe that Sherlock had gotten all of the answers he could  _possibly_  get from kissing him. So when Sherlock asked John to accompany him to a local indoor pool a few blocks away, he figured it was just going to be some experiment on the effect chlorine had on hair follicles or something along those lines.

Unfortunately, Sherlock _– accidentally_  – forgot to mention that the experiment was very similar to the one he had performed a few days back.

"Sherlock, it's 10 o'clock at night. Don't you think the pool will be closed?" John asked as they made their way down Baker Street.

Sherlock smirked, pulling a set of keys from his coat pocket and flashing it in John's face. "When half of London owes you favors, places are rarely off limits, regardless of time."

The doctor let out an annoyed sigh as he rolled his eyes. Sherlock had a seemingly endless string of resources at his disposal. If he would get on with Mycroft, he would surely be capable of getting away with murder.

John shuddered at that thought. ' _Note to self: Ensure that Sherlock and Mycroft_ _ **never**_ _become friends._ '

The sound of keys jingling shook John from his thoughts. He took a quick glance around and noticed that they had already reached the aquatic center.

Sherlock quickly unlocked the door and entered, John trailing quietly behind him. Once John made in, Sherlock locked the door.

While John was busy looking around, Sherlock reached into the bag he was carrying and tossed a pair of swim trunks at him.

"Go get changed into these," Sherlock demanded. He walked over to a wall behind the front counter and turned on most of the light switches.

"Where's the changing room?" John looked down at the swim trunks in his hands. "And where did you get these from?"

Sherlock began making his way down a hallway to their left.

"Follow me," Sherlock said, deliberately ignoring the second question.

\---------------

John finished dressing and placed the discarded clothes down in a pile on a bench. He made his way from the changing room, musing about how Sherlock had  _possibly_ managed to get the perfect-size swim trunks for him.

' _Oh well. It's just one of his quirks, I suppose,'_  John thought as he entered the main pool area.

"Go ahead and get in the pool, if you will," Sherlock said as soon as the door opened. He was currently seated on a bench, texting at an inhuman speed, presumably telling Mycroft off for questioning why they were at a pool at such a time.

Although, after what the two had gotten themselves into the  _last_  time they went to a pool so late at night, John could understand where Mycroft's worry was stemming from.

The doctor made his way over to the edge of the pool, tentatively dipping a toe in the water.

 _'Heated pool. Absolutely_ wonderful _.'_ John thought as he dropped the rest of his body into the water.

John swam around for a few minutes, simply enjoying the feel of the water, until Sherlock finished texting.

"Alright, so what I am studying is lung capacity," Sherlock said as he made his way over to the edge of the pool. "All you will have to do is take in a deep breath and float, belly-down in the water until you can no longer bear it."

John looked a bit confused as he asked, "Why couldn't I have just held my breath while sitting down somewhere? Not that I'm not enjoying the pool or anything. . . but why?"

"The way you will be floating in the water allows you to completely relax your limbs," Sherlock said as he pulled a stop-watch from his pocket. "And you can't exactly achieve that level of physical relaxation while you are on dry land."

John nodded as though he understood, but he still didn't  _quite_  get it.

"So, whenever you're ready, I need you to take in as deep of a breath as you can manage and then lay belly-down in the water. Your limbs should be completely at ease. They will be levitating; not straight down, and not on top of the water. Do  _not_  attempt to move them."

Sherlock continued, "Try not to think about anything in particular, either. Just relax as much as you can manage." He paused for a moment in thought. "In fact, think of this as a meditation exercise. Just allow your thoughts to shift naturally, and do not attempt to concentrate on any given subject; specifically if it's a negative one. I need you to continue holding your breath until you absolutely  _have_ to come up for air. Do you understand?"

John nodded. "So I can start now?"

"Feel free," Sherlock replied, his timer at the ready. "I will begin timing when you finish inhaling."

John took a second to concentrate. Although it was extremely straightforward, he did not want to muck things up the first go-round and be reprimanded by Sherlock for it.

He took in as deep of a breath as he could and floated face-down in the water, his limbs naturally levitating in the Limbo between the surface and the bottom of the pool. The silence that the water provided him with was peaceful; he could hear nothing except for the steady, slow beating of his heart.

' _Is my heartbeat always so loud? Do I simply tune it out? It's like the tempo to a song. . . A wonderful, deep song. . . I love this.'_ John's thoughts progressed slowly, aligning perfectly with his internal song. _'Maybe I should try this in the tub one day. . . I can feel the water slowly sliding across my arms and legs; the coolness makes it feel like a massage. That's exactly what this reminds me of! A massage. It's like a brain massage. . . Sherlock would enjoy this. I'll bet he has done this before, but I wonder if he was able to not think for a prolonged period of time? Not likely. His mind is magnificent, and it likely never shuts down. He's brilliant._ '

John's thoughts continued on for a few minutes until he was overcome by a sudden need for oxygen. He fought against the burn in his lungs, but after a few seconds, he found himself breaking the surface of the water and gasping in a much-needed breath.

Sherlock pressed the stop button as soon as John surfaced.

"You were able to hold your breath for two minutes and forty-three seconds. That's fairly decent for having no warm up," Sherlock said as he pulled out his cell-phone and typed out the time.

John was too busy trying to  _breathe_  to comprehend what Sherlock said, but he didn't care. The entire lightheadedness he was experiencing felt amazing, and the first breath he took in when he resurfaced was so incredibly satisfying. It was as though he had restarted his body and his mind, and John was certain that he had never felt anything like it before. He wanted nothing more than to experience it again.

"John?" Sherlock asked, pulling John from his thoughts.

He turned to face Sherlock. "Yes?" he asked, his breaths still coming in short and shallow rasps.

Sherlock raised an eyebrow at his flatmate, "Did you not hear me tell you the second half of the experiment just now?"

John blushed slightly, shaking his head no.

"I was thinking. My apologies," John said. "But I didn't know there was a second part. . . ?"

The lightheadedness was beginning to fade, and John was starting to feel uneasy. He had not been told that there would be any other part to the experiment, and he knew that could only be bad news for him.

"Before you lash out, I want you listen. Got it?" Sherlock asked, a stern look on his face.

John sighed but nodded nonetheless.

"To increase lung capacity, the quickest and most effective way is to breathe in as deeply as you can, hold it and then slowly breathe out through your mouth. As you may recall from a few weeks ago, I told you kissing is a light exercise, and when a person is kissing for prolonged periods of time, he or she unconsciously does something uncannily similar. It's not to the same extreme, but it gradually causes your lung capacity to increase."

"So, I need to test the theory to see what sort of changes there are in your lung capacity after we," Sherlock paused, trying to think of the best word, " _snog_  for ten minutes or so."

John almost laughed. He should have  _known_  this was going to happen.

' _What in the everliving Hell was I expecting when I came here? A simple swimming exercise? No. Of course not. This is_ Sherlock fucking Holmes  _we are talking about here. Nothing is ever so simple or comfortable when it comes to him._ '

"No." John said, folding his arms over his chest protectively.

Sherlock looked surprised.

"No?"

"Yes, Sherlock.  _No._  I'm not going to take place in any more of your little experiments so long as they have anything to do with kissing you."

John glared at his flatmate.

"And why ever not? It's not as though this will be the first time you have done it!" Sherlock complained, a confused, angry scowl on his face.

John gaped at him. "This is too much! Two minutes, fine. Five minutes, pushing it.  _TEN MINUTES?_ That's practically foreplay!"

"What the hell does  _time_  have anything to do with it? It's all the same in the end, is it not?" Sherlock asked, ever the logical one.

John simply stared at him, not entirely able to verbalize the thoughts that were passing through his mind.

' _The problem is that if we snog for that period of time, I may not be able to control my actions._ _ **That's**_ _the bloody problem, you smug git._ '

Sherlock waited for a response but only received a confused expression. He sighed in annoyance before asking, "What if I lower it to seven minutes? Will that suffice for your apparent 'limit'?"

John considered that for a moment.

' _You could manage that, John. That's just like when you were in secondary school, snogging that random bird at the party for Seven Minutes in Heaven or whatever. Come on, you're not attracted to him. He's so odd looking. And he's a complete arse-hole. You are_ _ **not**_ _attracted to him, John._ ' As he urged himself on in his mind, he found himself nodding.

Apparently not caring that John's nod was directed toward his inner dialogue, Sherlock exclaimed, "Great! We're settled then. Seven minutes. I'll give you five minutes or so to allow your breathing and your heart rate to get back to normal."

Before John even had a moment to utter a counter, Sherlock had left for the changing room, leaving John alone to wallow in self-pity.

\--------

Five minutes later, just as Sherlock had promised, he re-entered the pool area wearing nothing but some black swim trunks.

"Ready?" Sherlock asked, making his way toward the edge of the pool.

John tried – and failed – to not openly stare, but he had only seen shirtless Sherlock on a few occasions. His chest was just as pale as the rest of him, and John could tell that there were just as many scars there as there were on his arms and hands. The doctor in him worried about the infections that may have presented from the wounds, but the friend in him wondered who cared for him when he was injured, since he really had no other friends.

The sound of Sherlock getting in the pool stirred John from his thoughts, and he began feeling that familiar nervousness grip him, just as it had the previous two times. He could feel his heart hammering away in his chest, and he was beginning to worry that Sherlock would be able to feel it when they started kissing.

"Are you ready?" Sherlock asked when he reached John, wrapping the stop-watch around his neck and starting it at seven minutes and fifteen seconds.

' _No, but that wouldn't stop you from continuing your experiment anyway,_ ' John thought as he said, "As ready as I'll ever be."

John immediately felt Sherlock's lips meet his. For being "asexual," Sherlock worked an incredible amount of passion and sexuality into the kiss. John felt himself step even closer to his flatmate, their bodies flush up against each other as he moved his left hand to cup Sherlock's neck.

They kissed slowly, deeply, just familiarizing themselves with the sensation of kissing one another again. After a minute or so, John took a risk and slowly ran his tongue across Sherlock bottom lip,  _praying_  that he would be granted access. The detective's lips parted slowly, effectively allowing John to deepen the kiss.

When John's tongue met his, Sherlock let out a barely-audible groan.

' _Oh God. That sound. . ._ ' John thought.

He pressed his body closer to Sherlock's until there was literally no space between them, and his right hand began to wander over Sherlock's side, slowly moving across it until he reached his hip. Warmth radiated between the two as John continued to explore Sherlock's mouth, occasionally pulling back to take a quick breath.

The seven minutes came and went, neither paying much attention to the beeping of Sherlock's stop-watch.

A few minutes after the watch started its easily-ignored beeping, John pulled back, desperately needing to catch his breath. Sherlock reached for his stop-watch and turned it off, taking a hesitant step back from his flatmate.

John and Sherlock both cleared their throats simultaneously, attempting to dispel of some of the awkwardness that now surrounded them both.

The detective backed up until he reached the edge of the pool a few feet back and let out a polite cough.

"That was. . . good. You can, erm. . . hold your breath again once your breathing is," he coughed again, "back to normal."

John nodded silently, slightly confused by Sherlock's sudden stuttering problem, but too euphoric to care.

Although, John could have  _sworn_  he saw the faintest reddening of his flatmate's cheeks as he watched him climb out of the pool and make his way over to the nearby bench.

**Notes for the Chapter:**

> Next chapter: Sherlock needs to find out if saliva is actually an effective pain-reliever.


	4. A Study in Pain Relief

**Notes for the Chapter:**

> Disclaimer: I do not own Sherlock Holmes, John Watson or 221B Baker Street. Not in the slightest.
> 
> Warnings: Some mild cursing.
> 
> Word Count (this part): 1,556

The day after the pool experiment, John beat Sherlock to the punch.

John had just finished making tea and made his way into the sitting room to give Sherlock a cup. Sherlock sat crouched on his chair, his fingers steepled, and his eyes following every single move John made with utmost concentration.

John set the cuppa down on the table in front of Sherlock and sighed, looking down at his flatmate.

"I can tell by the look on your face that you are going to need me for an experiment again." John folded his arms across his chest. "Get on with it, then; what do you need me to do?"

Sherlock grinned up at him mischievously, "This one will be a bit more," he paused, " _odd_  than our previous ones."

John shook his head in disbelief, wondering how it could  _possibly_  get any more odd than it had already been.

"Care to elaborate, then?"

Sherlock continued to stare at John as he said, "I am going to bite my lip to a point in which it breaks the skin slightly; enough for it to hurt and bleed a tiny bit." Sherlock tilted his head slightly and pointed his steepled fingers in John's direction before continuing.

"Researchers have found a natural chemical in saliva called opiorphin, which is six times more potent as a pain-reliever than morphine. I need to test how quickly the opiorphin stops the pain versus how long it takes for a low level of morphine to take effect."

John glared down at Sherlock as he said, "I'm not going to let an ex-addict take morphine, Sherlock."

"This experiment  _must_  be done!" Sherlock said irritably. "Using opiorphin as a replacement for morphine could reduce the risk of addiction in people who use pain-relievers." He paused for a moment, a sly grin replacing the irritated look from his face. "You want that, do you not? Being a doctor and all?"

John considered it for a moment.

' _He's right, of course. Morphine_  is _extremely addictive, and it's overall not good for you. . . . But there's no way in **h** **ell** I'm letting Sherlock touch that stuff. Not since I know about his past._'

John was about to tell Sherlock no, strictly because he had no intention of allowing him to use the morphine afterward, but another thought wedged its way into his brain right as he was about to speak.

' _What if I refuse to take place in the experiment? He could easily find someone else who would let him use the morphine. . . . and there's no way I'm letting that happen_.'

With that thought, John made up his mind.

"I'll do it," John said. "But under one condition."

Sherlock quirked his head to the side in interest, his eyes slightly narrowed, "And what might that be?"

John folded his arms across his chest as he stared right back at Sherlock.

" _I_  receive the cut on my lip, and  _I_  take the morphine."

Sherlock's facial expression went from interested to confused. "Why?" He asked.

John shrugged. "You're an ex-addict," he said. "That makes you more likely to either relapse or find a new addiction in the pain-reliever. . . And I'm not going to let that happen."

Sherlock didn't have to be the world's only consulting detective to realize that John wasn't going to let him take the morphine. John had seen too much go wrong with his sister to even  _risk_  losing another person to addiction.

The detective stood up from his crouched position so he was standing with the back of his legs pressed against the chair.

"Fine," Sherlock said, clapping his hands together as he took a step toward his flatmate. "We'll have to wait a few days until I can get my hands on the morphine for the second half, anyway."

Sherlock suddenly reached out, gripped the front of John's jumper and pulled him close, causing the doctor's breath to hitch in surprise. A barely noticeable smirk played across Sherlock's lips, but John only had a fraction of a second to comprehend the undeniably  _smug_  appearance of it before his mind went completely blank.

Sherlock's soft lips met John's in a hungry, surprisingly aggressive kiss. The possessiveness that John could feel simply  _radiating_  off of Sherlock in that first moment nearly knocked him off his feet. The doctor realized that, while he may have never been one to take the submissive role, he was willing to let Sherlock do whatever the hell he damn well pleased if he continued to kiss him like that.

John felt himself being pushed backwards until the back of his legs met the resistance of the couch cushions. His lips briefly lost contact with Sherlock's as he fell back into a sitting position, but the detective quickly straddled John's lap and reattached their lips with the same aggressiveness that the last kiss had started with.

Sherlock placed his hands on either side of John's neck as he ran his tongue over the doctor's bottom lip, just as the latter had done to him at the pool the night before. As soon as John granted him access, he felt Sherlock quickly, _softly_  nip his bottom lip; not hard enough to draw blood or even remotely hurt, but enough for John to feel it. After a few seconds, Sherlock bit the spot again; harder this time. John could taste blood, but, while the spot stung slightly, it was by no means unbearably painful.

Sherlock suddenly pulled back from the kiss.

"On a scale of one to ten, how badly does it hurt?" The detective asked, his voice a bit deeper than normal.

John's eyes opened just as slowly as his thoughts became coherent. "About a three," he replied, his eyes focusing for a short second on Sherlock's enlarged pupils.

"Perfect," was all Sherlock said before bringing his lips back to John's.

Sherlock moved one of his hands from John's neck to the back of his head as he licked the slightly raised sore spot on his bottom lip. John shivered, the pleasure of kissing mixing beautifully with the sting of the cut. The doctor wanted more, however, so he leaned up a bit and captured Sherlock back in a proper kiss. For a few blissful moments, they kissed like they had the night before.

But Sherlock once more ruined it by pulling back.

"Does it still hurt, John?" Sherlock asked slowly, slightly breathless from the last kiss.

John took a moment to concentrate on the spot on his lip. Amazingly, there was no longer any sort of pain there. The surprised look that flashed across John's face was enough of an answer for Sherlock.

The detective scrambled off John's lap and pulled his phone from his pocket.

John heard Sherlock mutter, "25 seconds for the opiorphin to take full effect," as he watched his flatmate typing away on his phone.

"Thank you, John," Sherlock said, never taking his eyes off the phone. "You have been a  _tremendous_  help. . . I'll be sure to let you know when the morphine arrives in a day or two. Your lip should be fully healed by then."

With that being said, Sherlock made his merry way toward his bedroom, leaving an incredibly confused doctor in his wake.


	5. Chapter 5

**Notes for the Chapter:**

> Disclaimer: I do not own Sherlock Holmes, John Watson or 221B Baker Street. Not in the slightest.
> 
> Warnings: Some mild cursing.
> 
> Word Count (this part): 1,620

Sherlock was sitting downstairs watching crap telly when he heard the scream come from John's bedroom.

The detective jumped to his feet and made his way upstairs as quickly as he could. He burst through John's bedroom door, and quickly took in what he saw: John was tossing and turning in his bed, his bed-sheets strewn about, and sweat gleaning all over his body.

Sherlock made his way over to the bed and slowly reached out a hand, grabbing the still sleeping John's shoulder and shaking it slightly. "John," Sherlock said quietly, but the doctor didn't stir. "John!"

John jerked awake, his arms rising as though he was trying to shield himself from being hit.

Sherlock yanked back his hand from John's shoulder and stared down at his flatmate. "It's just me, John. It's all right. . ." He reached his hand back out and placed it on one of John's arms, slowly easing pressure onto it until John relaxed and let it fall down to his chest.

Once his arms were no longer shielding his face, Sherlock noticed the distinctive glisten of tears on his cheeks. He moved his hand up to John's face and slowly wiped the moisture from them with his thumb. John closed his eyes, trying hard to calm himself, but his breathing was still rapid from the nightmare he was just roused from.

"You're fine, John," Sherlock soothed, "You're at our flat on Baker Street, not back in Afghanistan. There are no casualties. . . " Sherlock ran his hand through John's short hair. "It's just us here, John. . . It was only a dream."

John slowly opened his eyes as his breathing became less labored, and he immediately directed his attention to Sherlock. The doctor reached out his right hand and wrapped it around the back of his flatmate's neck.

"Oxytocin and cortisol," was all John said before he pulled Sherlock down for a kiss.

As Sherlock kissed back, a stream of thoughts ran through his mind.

' _Oxytocin is the chemical that reduces one's anxiety and calms him or her down. Cortisol is the stress hormone. It lowers as oxytocin is secreted into the bloodstream, thus reducing stress even further. Kissing releases oxytocin, thus providing John's reason for kissing me; he needs to calm down_.'

John pulled back slightly and muttered, "Stop thinking, Sherlock," against his lips.

Sherlock obliged, bringing himself from the leaning position he had been in to a better suited kneeling position with his knees on the bed next to John. He moved his hand from John's hair to his neck, cupping it gently as he pulled him a bit closer. The kiss was slow and easy, neither attempting to push it past what it was.

Sherlock's mind was pleasantly blank, the buzz he was getting from the kiss muting any and all background noise that was usually present. The last four times they had kissed, his mind had this exact same response; the only thoughts that made their way through his brain were ones of John and how incredibly soft and lovely his lips felt against his.

The kisses gradually slowed until they stopped altogether. Sherlock brushed his lips against John's once more before he pulled back and rested his forehead against the doctor's, his eyes still lightly closed.

He massaged slow circles on John's neck with his thumb as they sat there, neither man moving for a few minutes as they simply enjoyed the comfort and the calmness they both felt from the kiss.

Sherlock pulled back and slowly opened his eyes, watching as John's eyes re-opened and focused on him. John smiled up at him and brushed his thumb over his neck.

"Thank you," John said. "I. . . I really needed that."

Sherlock grinned down at him in response. "I'm glad I could help," he said, "seeing as it was for science and all."

The smile on John's face faltered for a split second before he could stop it. Unfortunately for John, Sherlock's observational skills didn't fail him.

"What?" Sherlock asked, his head quirked slightly to the side with a questioning expression on his face.

John removed his hand from the side of Sherlock's neck and pushed slightly on his chest so he could sit up. Sherlock sat back, slight confusion still evident on his face as John moved to a sitting position.

"I uh. . . I need to tell you something." John cleared his throat as he felt his cheeks begin to redden. "I didn't just. . . I want to tell you that I uhh. . ." He faltered once more, not entirely sure how he was going to phrase what he was going to say. "The kiss wasn't just for. . . Um. . . It wasn't  _just_ for science, Sherlock."

Sherlock's face went from one of mild confusion to one of complete comprehension.

John kept talking. "I  _did_  need to calm down. The nightmare was so realistic, and it just. . . you were being tortured to death, and I couldn't do anything to stop it." Sherlock simply stared at John as he continued. "So when I woke up and you were here, and you were  _all right_ , and I was at home with you, I. . . I just realized how much I need you. And I know you probably think I'm some patheti-"

John was cut off when Sherlock swiftly leaned forward and kissed him. It only lasted a second, but it was long enough to shut John up, just as Sherlock needed.

"It's fine, John," Sherlock said, his mouth still hovering close to John's. "It's  _all_  fine."

A grin broke out across John's face, and he quickly removed the small space between their lips once more.

Sherlock placed his hand back on John's neck, pulling him close. The pleasant silence he was usually greeted with whenever he kissed John was replaced with a semi-guilty thought.

' _You_ _have to tell him. He told you his true motive, so he has the right to know yours_ _._ '

Sherlock pulled away from the kiss and leaned back so he was a foot or so away from his flatmate. "John, I have a confession to make as well. . ."

The doctor's eyes widened at Sherlock's tone, and he mentally reprimanded himself for telling him the real reason he kissed him. Nonetheless, he nodded, urging Sherlock to continue.

"I haven't been entirely truthful with you, John." He paused for a moment, looking away from his flatmate. "Those experiments I have had you partake in these past few weeks. . . Um. . . They weren't exactly  _real_."

John's jaw dropped, his eyes wide as he stared at Sherlock in shock.

Sherlock continued, "The first one was real, of course, but the others I. . . I made them up. I created some realistic-sounding experiments, hoping they would make enough sense that I could persuade you to let me kiss you again." He slowly brought his gaze back to John, who was still openly gaping at him. "I would understand if you are angry with me for misleading you, but I had to do it. I just had to know. You wouldn't get out of my head, and it was interfering with my work."

John shook his head in disbelief. "I can't believe you!" He gasped. For a moment, he tried to appear angry, but he couldn't keep up the facade, and he broke down into laughter.

To say Sherlock looked confused was an understatement.

"How could this possibly be humorous to you?" Sherlock asked.

John attempted to hold himself together as he said, "I just. . . We are both so pathetic." He laughed again. "You're telling me that we could have been doing this the  _whole goddamn time_?"

John's laughter started breaking down Sherlock's walls, and he began to chuckle as well. "It seems as though we were both having some internal conflicts we were trying to resolve. . . I could say that we have come to some conclusions, have we not, John?"

John wrapped his hand around Sherlock's neck, leaning back until he was lying down with the detective hovering over him once again.

John grinned impishly up at him.

"You know, Sherlock. . . " John said, pulling him closer until their lips were less than a hair's breadth apart. "For an idiot, you're pretty damn smart."

**Notes for the Chapter:**

> A/N: Well, that's the end! I hope you all enjoyed it.

**Author's Note:**

> Sphygmomanometer – A device used to measure blood pressure, comprising of an inflatable cuff to restrict blood flow and a mechanical manometer to measure the pressure.  
> Stethoscope - A medical instrument for listening to the action of someone's heart or breathing.  
> Systolic pressure – The blood pressure when the heart is contracting.  
> Diastolic pressure - The blood pressure when the heart is relaxed.
> 
> Next chapter: Sherlock needs to test the effect kissing has on O2 saturation.


End file.
